1. Field of the Invention
The invention relates to a ceramic lining for thermally highly-stressed walls of combustion chambers. Such linings are used in particular as an internal wall insulation of metallic combustion chambers, for example for gas turbines.
2. Brief Description of the Related Art
Combustion chamber walls may be designed with polygonal surface elements of ceramic material or metal. The number of corners of these elements is usually 3 or 4. But hexagonal surface elements are also known. These surface elements are structured like a plate and are attached to the metallic support structure with a separate bolt.
DE 195 02 730 A1 describes, for example, a ceramic lining of a combustion chamber consisting of at least one wall plate of high-temperature-resistant structural ceramic, also called monolithic ceramic, with at least one continuous opening and one attachment element per opening. The attachment element is attached by its foot in a metallic retention device provided on a metallic support wall, whereby the head of the attachment element rests in the opening of the wall plate. The attachment element also consists of high-temperature-resistant structural ceramic and is connected spring-elastically to the retention device. An insulation layer of fiber ceramic is provided between the metal wall and the ceramic wall plate.
The advantages of this solution are that the lining can be uninstalled without destroying it and therefore can be used several times. The spring-elastic connection of the ceramic structure with the metallic retention construction furthermore makes it possible for the thermal expansions between metallic and ceramic components or deformations of the insulation layer through mechanical stresses to be absorbed.
These advantages are counteracted by the disadvantages that the attachment of the lining on the metallic support structure is relatively complex because of the separate bolt and retention device, and that the lining is complicated because it requires several layers.
Because of the plate structure, the insulation layer on the side facing away from the hot gas also must be constructed from plates in a ceramic design of the combustion chamber. The usually porous structure of the insulating material makes the insulation plates sensitive to vibrations, which may cause a breaking of the parts. It is also necessary that retainers for the insulation are provided.
In addition, the hot-gas-conducting, plate-shaped combustion chamber tiles are also very sensitive to vibrations and damage due to foreign parts, since the plates are very thin and fragile.